AN3232

Epoxy sealed, non-hermetic RF power packages

Doc ID 17594 Rev 3

5/26

1

Epoxy sealed, non-hermetic RF power packages

Epoxy sealed products, such as the STAC package family, should be received in an N2-

backfilled, vacuum-sealed ESD bag containing a desiccant. This decreases the possibility of

moisture uptake by the package materials during transit and long-term storage. STAC

packages carry a moisture sensitivity rating of 3 (MSL3), but have demonstrated capabilities

of up to MSL1.

Even with such shipping methods, it is advised to store epoxy sealed packages in the

original containers, or in a dry box, until required for soldering. When the environmental

history of devices is not well-known, such as after a prolonged storage period, it is a well-

practiced safety measure to bake non-hermetic packages for 24 hrs at 125 °C prior to

soldering operations. These conditions can be accelerated or lengthened as a function of

temperature, up to the limits imposed by shipping containers, by trays, or by device

maximum ratings. Refer to Figure 2 for recommended baking conditions.

Figure 2.

Drying times

Under no circumstances should any epoxy-sealed package be treated as a hermetically

sealed package, due to the fact that such sealing materials are not impervious to moisture

ingress. However, it is important to point out that RF Power packages are typically

constructed using engineering ceramics and polymers which, on their own, demonstrate

high resistance to moisture penetration, such as the proprietary liquid crystal polymer

materials upon which STAC packages are realized.